Robustness of a communications network is a network characteristic to which a communications operator pays much attention. To enhance the robustness of the communications network, the communications operator usually establishes a standby path or a standby network for a communication path or a communications network during networking, and the standby path or the standby network is used to protect a service transmitted on the communication path or the communications network when a fault occurs in the communication path or the communications network.
As communications technologies change quickly, communications networks become more diversified and complex. Meanwhile, network protection technologies are also confronted with many new challenges.
As shown in FIG. 1, FIG. 1 exemplarily provides a communications network. In FIG. 1, a node A, a node B, and a node C are sequentially connected, where the node A and the node B are connected to each other using a working path (working path, indicated using W1 in the figure) and a protection path (protection path, indicated using P1 in the figure), and the node B and the node C are connected to each other using a working path (working path, indicated using W2 in the figure) and a protection path (protection path, indicated using P2 in the figure). Normally, a service sent by the node A to the node B is transmitted using the working path W1, and when a fault occurs in the working path W1, the node B starts protection switching, to switch the service from the working path W1 to the protection path P1, implementing service protection. Communication between the node B and the node C is normal and protection switching does not need to be performed.
However, during actual network operation, when the node B performs protection switching, the node B cannot normally send a signal to the node C in a particular period of time because of a known or an unknown reason such as clock switching or path switching. Additionally, due to a length difference between primary and secondary optic fibers and other reasons, it is possible that the node C erroneously determine that a fault occurs in W2, and then performs protection switching between W2 and P2. It can be learned that, in the prior art, protection switching between nodes may be erroneous switching sometimes, and accuracy of the protection switching is relatively low.